Measurement of pressure in fluidic environments, which can include either gaseous or liquid conditions, has been addressed by numerous ways and means. Of particular interest in measuring fluidic environments through the years has been the use of mechanical devices which react to a difference between an ambient environmental or control pressure and a closed or otherwise constrained test environmental pressure. Mechanical devices are advantageous in that such equipment is conducive to mass production, offers increased durability and consistency in performance, and can be readily applied to various pressure measurement applications.
Adaptation of mechanical pressure measurement devices is of particular importance when dealing with a gaseous system which is either adversely affected by pressure extremes or it is critical to maintain a gaseous system within required upper and lower levels. In such sensitive applications, the mechanical device must be responsive to small changes in pressure and readily/repeatedly indicate the pressure measurements of the gaseous environment in a clear and concise way. Further, where it is necessary to determine sudden changes in pressure, the device must be capable of indicating such changes immediately and accurately at the time as such occurs.
One system wherein sudden, small and repeated pressure changes are significant in interpreting overall performance attributes is the respiratory system of a human patient, wherein the measuring device is used in the form of a pressure measuring manometer. Prior pressure measuring manometers have utilized a number of different mechanical actions to indicate respiratory pressure measurements with differing levels of efficiency and effectiveness. U.S. Pat. No. 5,535,740 to Baghaee-Rezaee utilizes a bellow-type pressure gauge utilizing a bifurcated port to measure either a positive or negative pressure change. U.S. Pat. No. 5,557,049 to Ratner utilizes a diaphragm associated with a spiral shaped actuator stem and a top-down visible flat radial dial indicator. U.S. Pat. No. 5,606,131 to Pope employs a sliding, spring biased piston enclosed in a tube having pressure measurement indicia printed thereon.
The aforementioned pressure manometers each offer a means for displaying pressure changes in a respiratory circuit or ventilation environment. However, there remains an unmet need for a pressure manometer for measuring patient lung performance that is simple to use, sensitive, efficient, accurate and reliable over a continuous period of cycling.